[exim] How to invoke an Exim Filter from an alias file?

Hello,

I there a way to "invoke" an Exim Filter File from an alias file?

I'd like to have a special directive with the filter file on the
right hand side of an alias file entry, that causes Exim to read
in the Filter File and continue as if it was found in a .forward

Something like:

user:        use-filter:/path/to/filterfile

I gather from the manual that the redirect router proceses filter code,
if that code is the result of an expression in the data option.
So maybe it can be done with some wicked string expansion?

(Background:
I have a mail domain that gets serviced out of a big forward file,
and I want to add an autoresponder to one address of that domain.
And I'm really fond of the Exim Filter autoresponder facility.)

Thanks,

Florian